Optical disc drive compatible with memory card slot

ABSTRACT

A disc drive designed to hold a cartridge containing an optical data storage disk is compatible with a memory card slot in a host digital electronics device such as a PDA, for example a slot designed for a Type I CompactFlash card. The disc drive contains a body assembly which is inserted into the memory card slot and which has a compatible connector at one end. The disc drive also includes a drive mechanism which contains the spindle motor and optics systems and which is located outside the memory card slot when the drive is in operation. The drive mechanism is lifted from the body assembly to form an opening to a tray into which a cartridge is loaded. The drive mechanism is then pressed against the body assembly to close the cartridge tray and to cause the spindle motor assembly to engage the optical disc within the cartridge. To minimize the extent to which the disc drive protrudes from the host device, part of the cartridge extends into the memory card slot when the disc drive is connected to the host.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to application Ser. No. ______[Attorney Docket No. VMA004US], which is co-owned and filed concurrentlyherewith, and which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] This invention relates to high-volume data storage and, inparticular, to a disc drive that is compatible with an industry-standardmemory card slot of the kind found in portable computing devices.

BACKGROUND OF THE INVENTION

[0003] Consumer entertainment technologies are moving towards highresolution color displays for mobile entertainment. Increasingly,consumers want to take their entertainment with them. Cross-countrytravelers and cross-town commuters are eagerly pursuing gaming, musicand video entertainment activities on cell phones, personal digitalassistants (PDAs) and portable computers. At present, however, theentertainment experience is limited, even primitive, compared to whatconsumers have come to expect from their game consoles, home theatersand DVD-equipped computers.

[0004] The main problem is data storage. The fact is that sophisticateddigital entertainment is data-intensive, and it is growing more so everyday. Traditional small “form factor,” portable media such asCompactFlash® cards, SD® flash cards, Memory Stick™ and other solidstate memory devices simply cannot deliver the capacity and price permegabyte required for a high-quality entertainment experience. Recordingcontent onto solid state memory cards in high volume is expensive andimpractical, and securing that content effectively is very difficult.

[0005] While some experts predict that broadband Internet access willdeliver high-quality games and movies to mobile consumer electronicsdevices, there are significant barriers to success. Cell phone networksare designed to transmit voice communications and are simply notefficient for high-capacity data transmission. Cell connections are notcapable of the required speeds and are notoriously unreliable, withfrequent dead zones and dropped connections. While games are beingdelivered to cell phones currently, the quality of game play and thegame environment cannot begin to approach that of a console.

[0006] WiFi, or 802.11, wireless is designed for data transmission, andthe growing number of WiFi hotspots looks attractive on the surface fordelivering large amounts of data to mobile devices. Internet access andemail application for multiple users are easily accommodated by WiFi.Nonetheless, managing streaming and interactive content such asmultiplayer games and high-quality video or movies for thousands, if notmillions, of users simultaneously will be challenging for any network.Security is also a problem for WiFi, leaving content providers open topotential piracy.

[0007] Moreover, the data storage problem would still exist. For anysort of networked delivery system to be viable, mobile consumer deviceswill have to embed significant amounts of storage to hold large,downloaded game and movie files, and to track a player's progress withinthe game. Perhaps the most significant problem for networked contentdelivery is cost. It has been estimated that it can cost more than $30to send a DVD-quality film over the Internet.

[0008] Disc-based distribution costs are far lower. Even more compellingis the fact that consumers have consistently demonstrated theirpreference for purchasing high-value content on discs, as evidenced bythe recent upswing in DVD sales. Moreover, optical discs are molded andcan therefore be replicated at less expense than solid state memorydevices.

[0009] Clearly, the mobile entertainment industry needs an economical,small form factor, secure storage technology to meet the growing demandfor a portable, high-quality entertainment experience. In addition, itis anticipated that a storage device capable of holding large amounts ofdata would find application in other areas, such as in portablecomputers used in connection with the homeland security effort.

SUMMARY OF THE INVENTION

[0010] This invention melds the convenience and versatility of memorycards with the data storage capacity of optical discs. A drive for anoptical data storage disc is made in a form that is compatible with astandard memory card slot used widely in PDAs and other portable digitaldevices.

[0011] The disc drive of this invention comprises a body assembly and adrive mechanism. The body assembly is shaped and sized so as to fit intoa standard memory card slot. A connector compatible with the memory slotis positioned at a first end of the body assembly. The body assemblyalso includes a cartridge tray for receiving a cartridge that containsan optical data storage disc (sometimes referred to as an “opticaldisc”).

[0012] The drive mechanism includes a spindle motor assembly forrotating the disc and an optics system for reading data from the disc.The drive mechanism is attached to a second end of the body assemblythat is opposite to the first end where the connector is located. Thedrive mechanism moves between an open position and a closed position.Before a cartridge is inserted into the drive, the drive mechanism ismoved to the open position, and after the cartridge has been insertedinto the drive, the drive mechanism is moved to the closed position.Moving the drive mechanism to the closed position causes a collet toextend into a central hole of the optical disc. When the drive mechanismhas been fully closed, the collet grips the edges of the central holethereby enabling the spindle motor to spin the disc. In one embodiment amanual force is used to move the drive mechanism from the open positionto the closed position, eliminating the need for a separate motor andmechanism to perform this function.

[0013] In one embodiment, when the cartridge has been inserted into thedrive, a portion of the cartridge and optical disc extend into thememory card slot. In this way the portion of the drive that extendsbeyond the entrance to the card slot is minimized.

[0014] The optical disc rotates at a relatively slow speed (e.g.,400-500 rpm) as compared with magnetic discs, which rotate at 5000-7000rpm, for example. Therefore the power requirements of the disc drive ofthis invention are relatively modest (e.g., 100 mWatts). In comparison,a magnetic micro disc drive may consume on the order of 1 Watt of power.This makes the disc drive of this invention more useful with portableelectronics devices such as PDAs, where power consumption is an issue.

[0015] The drive is preferably compatible with a slot that is designedto accept a CompactFlash® CF Type I card, a small form factor card usedin many PDA devices. To meet this specification the portion of the bodyassembly that extends into the card slot has a width of approximately 36mm and a thickness of approximately 3.3 mm. Rails that are integral withthe body assembly slide along the sides of the CompactFlash slot, and astandard CompactFlash 50-pin connector is used to provide the electricalconnections to the host device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a view of the disc drive of this invention.

[0017]FIG. 2 is a view of the disc drive and a cartridge beforeinsertion of the cartridge into the disc drive.

[0018]FIG. 3 is a view of the top cover of the body.

[0019]FIG. 4A shows the cartridge receiver assembly, with the ejectlever relaxed.

[0020]FIG. 4B shows the cartridge receiver assembly, with the cartridgeinserted and the eject lever compressed.

[0021]FIG. 4C shows the cartridge receiver assembly, with the cartridgeinserted and latched.

[0022]FIG. 5 is an exploded view of the cartridge tray assembly.

[0023]FIG. 6 is a view of the cartridge tray and spring arm.

[0024]FIG. 7 is a cutaway view of the cartridge inserted in thecartridge tray to the point where the shutter latch begins to disengage.

[0025]FIG. 8 is a cutaway view of the cartridge and cartridge when thecartridge has been inserted slight beyond the point shown in FIG. 7.

[0026]FIG. 9 is a view similar to FIG. 8 except that the housing of thecartridge is shown.

[0027]FIG. 10 is a view of the cartridge and cartridge tray when thespring arm has just contacted the leading edge of the cartridge.

[0028]FIGS. 11 and 12 are views of the cartridge and cartridge tray whenthe cartridge has been fully inserted.

[0029]FIG. 13 is a detailed view of the shutter latch when the cartridgehas been fully inserted into the cartridge tray.

[0030]FIG. 14 is a view of a portion of the body assembly.

[0031]FIG. 15 is an exploded view showing major components of bodyassembly.

[0032]FIG. 16 is view of the body assembly.

[0033]FIG. 17 is a cross-sectional view of the disc drive.

[0034]FIG. 18 is a view of the drive mechanism from the bottom.

[0035]FIG. 19 is a view of the drive mechanism from the top with thecover piece and upper PCBA removed.

[0036]FIGS. 20A and 20B show the closed and open positions of the drivemechanism, respectively.

[0037]FIG. 21 is a cross-sectional view of the drive mechanism.

[0038]FIG. 22 is an exploded view of the drive mechanism.

[0039]FIG. 23 is a view of the coarse tracking mechanism and spindlemotor assembly.

[0040]FIG. 24A is an exploded view of the spindle motor assembly.

[0041]FIG. 24B is a detailed view of the expandable collet that is usedto grip the central hole of the disc.

[0042]FIG. 25 is a general view of the optomechanical carriage assembly.

[0043]FIGS. 26 and 27 are exploded views of the optomechanical carriageassembly.

[0044]FIG. 28 is a schematic view of the optics assembly.

[0045]FIG. 29 shows the quarter-wave plate.

[0046]FIG. 30 shows the objective lens mount.

[0047]FIG. 31 shows the respective positions of the laser diode andtracking photodetector on the laser diode/detector substrate.

[0048]FIG. 32 is a view of the fine tracking/focus mechanism.

[0049]FIG. 33 an exploded view of the fine tracking/focus mechanism.

[0050]FIG. 34 is a view of the latch mechanism.

[0051]FIG. 35 shows an embodiment in which a linear voice coil motor isused to move the optomechanical carriage assembly.

[0052]FIG. 36 illustrates a disc drive of this invention inserted into apersonal digital assistant (PDA).

[0053]FIG. 37 is a cross-sectional view of the disc drive and PDA shownin FIG. 36.

[0054]FIG. 38 is a bottom view of the PDA without the disc drive,showing the characteristics of the memory card slot.

[0055]FIG. 39 shows a cross-sectional view of an optical disc cartridgethat can be played in the disc drive.

DESCRIPTION OF THE INVENTION

[0056]FIG. 1 shows a perspective view of a disc drive 20 according tothis invention. Disc drive 20 includes a drive mechanism or “pod” 22 anda body assembly 24. Drive mechanism 22 includes the mechanical andoptical components of disk drive 20, described below. Body assembly 24is sized and shaped to fit into an industry-standard memory card slot,in this case a slot designed to accept a Type I CompactFlash® storagecard, used in many PDA devices. A Type I CompactFlash card has 50 pinsand measures 42.8 mm (1.7″)×36.4 mm (1.4″)×3.3 mm (0.13″). TheCompactFlash specification can be obtained athttp://www.compactflash.org/specd11.htm or from the CompactFlashAssociation P.O. Box 51537, Palo Alto, Calif. 94303. (See CF+ andCompactFlash Specification Revision 1.4, incorporated herein byreference in its entirety.) This invention is not limited to anyparticular type of slot, however. In other embodiments, the body can bedesigned to fit other types of slots. The dimension X1 of body assembly24 is actually inserted into the slot; the remaining portion, denoted bydimension X2 protrudes from the slot and therefore can be somewhatthicker. It is desirable to that the dimension X2 be as small aspossible, however, to minimize the amount of “overhang” from the PDA orother device into which disc drive 20 is inserted. Thus, a key featureof this design is that it is compatible with a standard Type ICompactFlash® slot on existing and future PDA devices, and adds aslittle volume and physical extension to the outside of such a device aswe have found practicable, while allowing removable media to be insertedin this device for variable program material.

[0057] In one embodiment the dimension X1 is approximately 40 mm and thedimension X2 is approximately 28 mm. The width Y of disc drive 20 is42.8 mm and the thickness Z1 (see FIG. 17) is approximately 3.3 mm.Since the dimension of a Type I CompactFlash® card in the insertiondirection is 36.4 mm, a clearance of 3-4 mm (40-36.4) is allowed betweenthe lateral face of drive mechanism 22 and the adjacent surface of ahost device such as a PDA. While the embodiment described herein iscompatible with a Type I CompactFlash slot, it will be understood thatconsonant with this invention a disc drive may be made compatible withany other type of memory card slot including industry-standard slotssuch as the Type II CompactFlash and PCMCIA slots.

[0058] At one end of body assembly 24 is a connector 26 with a socketarrangement that compatible with a Type 1 CompactFlash® pin arrangement.

[0059]FIG. 2 shows drive 20 along with a cartridge 10, which includes ashutter 108 on its top side. Cartridge 10 may be a cartridge of the kinddescribed in the above-referenced application Ser. No. ______ [AttorneyDocket No. VMA004 US], which is designed to hold a 32 mm diameteroptical data storage disc, although this is not required.

[0060] Cartridge 10 is inserted into disc drive 20 in the direction ofarrows 204 shown in FIG. 2. Drive 20 has been opened by squeezing thetwo “side” release buttons 202 toward one another. Squeezing releasebuttons 202 releases latches which hold drive mechanism 22 down, andallows a lift spring to move the drive mechanism 22 upward to a stop.That opens a space leading into a cartridge receiver assembly (notshown) and allows the insertion of cartridge 10. Cartridge 10 ispresented with the side that includes shutter 108 facing upward, and isinserted into disc drive 20. In the embodiment described, the traveldistance of drive mechanism 22 between the open and closed positions isapproximately 4 mm.

[0061] The cartridge receiver has a fixed “tab” which disengages ashutter latch (not shown), and moves shutter 108 to the open position asit is inserted in drive 20. If the tab does not enter a slot accessdisengagement of the shutter latch, the tab precludes the insertion ofcartridge 10 into drive 20. Thus, as described below, presentingcartridge 10 with the opposite (label) side up will result in arrestedmotion of cartridge 10 at approximately half of the insertion depth.

[0062] Linear motion of drive mechanism 22 in a direction perpendicularto the plane of body assembly 24 allows cartridge 10 to be replaced byanother cartridge while our drive is inserted into a PDA or other typeof digital appliance. In another embodiment, described below, the drivemechanism moves in an arc about a pivot axis transverse to the insertiondirection of the drive 20 and parallel to the primary plane of bodyassembly 24. This approach has some advantages in the areas ofsimplicity and durability, but it does not as easily allow mediaexchange while the CompactFlash connector is engaged.

[0063] We now describe in detail the components of disc drive 20.

[0064] Cartridge Receiver Assembly

[0065] The guides for the vertical motion of the drive mechanism 22, aswell as the latching details, are integrated into a top cover 206 ofbody assembly 24, which is preferably formed of sheet metal. FIG. 3shows top cover 206 with guides 210 extending upward. An invertedT-shaped slot 212 is cut into each of guides 210. Slots 212 serve aslocking features. Side release buttons 202 are affixed to leaf springswith features which latch into the transverse portion of the invertedT's and slide along the vertical portion of slots when the lockingfeatures are retracted. Also shown in FIG. 3 is an opening 214, which isused for reading the data area of a disc.

[0066] Top cover 206 has a cartridge tray 208 and other featuresattached to it, together comprising a cartridge receiver assembly 218,shown in FIGS. 4A-4C. As shown in FIGS. 4A and 4B, the insertion ofcartridge 10 opposes a cartridge eject spring arm 220 at the rear ofcartridge tray 208. This may occur, for example, when cartridge 10approaches within eight millimeters of full insertion. To facilitateremoval of cartridge 10, spring arm 220 provides the same eightmillimeters of motion to partially eject cartridge 10 from disc drive 20when the drive mechanism 22 is opened. When cartridge 10 is fullyinserted in cartridge tray 208, a retention “barbed” spring 222restrains the cartridge in the receiver. Spring 222 is visible in FIGS.3 and 4C near the forward edge of top cover 206. A matching notch in thecartridge engages spring 222 to retain the cartridge in cartridge tray208.

[0067] Referring to FIGS. 4A and 4B, a leaf spring 224 is visible on theside of cartridge tray 208. This is another barbed leaf spring, but witha less aggressive engagement angle on its face than leaf spring 222.Leaf spring 224 provides friction and purchase to ensure that shutter108 remains in place while cartridge 10 is ejected, thereby ensuringthat the shutter latch is reengaged. The friction of leaf spring 224also prevents cartridge 10 from attaining excessive velocity when it isbeing ejected by spring arm 220. It is desirable that the cartridge 10be offered for removal by the user, but not be “launched” from discdrive 20.

[0068]FIG. 5 shows an exploded view of cartridge receiver assembly 218.Leaf spring 224 has a barb 242 which projects inward through arectangular cutout 244 in the side wall of cartridge tray 208 and whichengages a rectangular window 140 in shutter 108, visible in FIG. 2. Leafspring 222 has a barb 240 which projects through a rectangular opening238 in top cover 206 and engages a notch in the top surface of cartridge10, i.e., the surface on which shutter 108 is located. Cartridge 10 isinserted into an opening 246 at the end of cartridge tray 208. Alsoshown in FIG. 5 is spring arm 220, which rotates about a pin 230. Pin230 is spot-welded to top cover 206. Spring arm 220 is biased by aspring 226, which is compressed between a stop 228, also spot-welded totop cover 206 and a tab 250, shown in FIG. 4B. Spring 226 biases springarm 220 so that a contact surface 234 extends through an opening 236 incartridge tray 208 when spring arm 220 is in a relaxed position (i.e.,with no cartridge inserted in cartridge tray 208).

[0069] An opening 248 is formed in a side of cartridge tray 208, and aguide 252 projects inward into the interior of cartridge tray 208. Guide252, shown more clearly in FIG. 6, performs two functions: First, whencartridge 10 is inserted into cartridge tray 208, a recess on one edgeof cartridge 10 rides over guide 252. Thus if the user attempts toinsert cartridge 10 improperly, either upside down or trailing edgefirst, guide 252 will block the insertion. Second, a ramp 254 is formedat one end of guide 252. When cartridge 10 is inserted, ramp 254 slidesalong an opposing surface of a shutter latch in cartridge 10 so as torelease the shutter. FIG. 7 is a view of cartridge 10 with the housingand other elements removed to reveal the positions of a shutter 180 anda shutter latch 114. FIG. 7 shows the position of shutter 180 andshutter latch 114 when cartridge 10 has been inserted to the point ofshutter release. As indicated, a surface 160 of latch 114 contacts ramp254, causing latch 114 to rotate in the direction of the arrow about apivot axis 190 and disengaging features of shutter 180 and latch 114which are normally interlocked so as to prevent shutter 180 from slidingopen. A disc 116 is also shown in FIG. 7. A complete description ofcartridge 10 is provided in the above-referenced application Ser. No.______ [Attorney Docket No. VMA004 US]. FIG. 7 shows spring arm 220 inthe relaxed position, pressed by spring 226 against the back edge ofcartridge tray 208.

[0070]FIGS. 8-13 show successive positions of shutter latch 114 ascartridge 10 as it is inserted into cartridge tray 208. FIGS. 8, 11 and13 are cutaway views similar to FIG. 7, where the housing and otherelements of cartridge 10 have been removed to reveal the positions ofshutter 180 and shutter latch 114. In FIG. 8, surface 160 of latch 114has just cleared ramp 254. FIG. 9 is a similar view with the housing ofcartridge 10 included, showing in addition a recess 256 of cartridge 10that rides over guide 252, as described above. Surface 234 of spring arm220 has not yet contacted the leading edge of cartridge 10. Barb 242 ofleaf spring 224 is sliding against a surface of shutter 180 but has notyet become engaged with window 140. Therefore, shutter 180 is stillcompletely closed.

[0071]FIG. 10 is similar to FIG. 9 but shows the situation whencartridge 10 has been inserted slightly further to the point wheresurface 234 of spring arm 220 just contacts the leading edge ofcartridge 10. Shutter 180 is still completely closed. It is thusapparent that latch 114 becomes disengaged, freeing shutter 180 to open,before barb 242 of leaf spring 224 engages window 140 of shutter 180 andbegins to pull shutter 180 open. In one embodiment, cartridge travelsapproximately 1.2 mm between the time at which latch 114 becomesdisengaged and the time at which shutter 180 begins to open. FIG. 10also shows leaf spring 222 and barb 240, as well as a recess 193 incartridge 10, which will become engaged with barb 240 when cartridge 10is fully inserted into cartridge tray 208.

[0072]FIGS. 11-13 show the state of affairs when cartridge 10 has beenfully inserted into cartridge tray 208. Surface 234 of spring arm 220 ispressed against the leading edge of cartridge 10 and has been rotatedagainst the force of spring 226. Barb 242 of leaf spring 224 has engagedwindow 140 of shutter 180 and pulled shutter 180 open, exposing the dataarea and a central hole 116A of disc 116. As shown in FIG. 12, barb 240of leaf spring 222 is lodged in recess 193 of cartridge 10, holdingcartridge 10 securely in cartridge tray 208.

[0073] Body Assembly

[0074] Disc drive 20 includes two basic components, body assembly 24 anddrive mechanism 22. FIG. 14 shows a portion of the body assembly 24,which includes a standard connector 26, which in this embodiment is a50-pin CompactFlash connector, a lower housing 260 and a printed circuitboard assembly (PCBA) 262, with the required integrated and discretecircuitry. In the embodiment shown, PCBA 262 essentially runs the lengthof body assembly 24. The rounded notch 264 in the forward edge of lowerhousing 260 is to make full insertion of the cartridge easier. Lowerhousing 260 has a first portion 266, which is generally sized and shapedto fit into a CompactFlash slot, and a second portion 268, which is notnecessarily designed to fit into a CompactFlash slot. The lateral edges267 of lower housing 260 function as integral rails that slide along theside walls of a CompactFlash slot as disc drive 20 in being insertedinto the slot.

[0075]FIG. 15 is an exploded view showing major components of bodyassembly 24. Included are top cover 206, cartridge tray 208 (attached tothe underside of top cover 206), PCBA 262, housing 260, connector 26, abottom cover 270, and barbed spring 222. Connector 26 fits into a recess272 in housing 260 and is attached with an adhesive. Like top cover 206,bottom cover 270 is preferably made of sheet metal. Also shown in FIG.15 is drive mechanism 22.

[0076]FIG. 16 shows body assembly 24 assembled, with top cover 206attached to lower housing 260. Top cover 206 may be attached to lowerhousing 260 by an adhesive or threaded fasteners or by the welding oftabs between top cover 206 and bottom cover 270. As will be apparent,cartridge 20 is off-center in disc drive 20 to accommodate the passageof circuitry to drive mechanism 22 and to allow full travel of theoptomechanical carriage assembly in drive mechanism 22 (described below)over the data band on the disc 116.

[0077]FIG. 17 is a cross-sectional view of disc drive 20, taken atsection line 17-17 shown in FIG. 1. As indicated, the horizontaldimension X2 of drive mechanism 22 substantially coincides with thewidth of the second portion 268 of body assembly 24. As noted above, thedimension X1 is approximately 40 mm. The thickness Z1 of the firstportion 266 of lower housing 260 is 3.3 mm, and this dimension increasesby approximately 0.7 mm in the thicker portion 268. Thus, in thisembodiment the second portion 268 of body assembly 24 is about 4 mmthick, slightly thicker than the first portion 266 of body assembly 24.This allows additional space for internal components of disc drive 20.The overall height Z2 of the drive in the area of drive mechanism 22 is10.5 mm.

[0078] When disc drive 20 is fully inserted into a CompactFlash® slot,the entrance to the slot is located near the line of intersection offirst portion 266 and second portion 268 (see FIG. 37). Thus cartridge10 and particularly disc 116 would protrude into the CompactFlash® slot.This limits the protrusion or “overhang” of disc drive 20 from the PDAor other device in which the slot is formed. Also shown in FIG. 17 arethe positions of top cover 206, PCBA 262 and bottom cover 270.

[0079] The foregoing is shown graphically in FIGS. 36 and 37. FIG. 36shows disc drive 20 inserted into a PDA 30, and FIG. 37 is across-sectional view of disc drive 20 and PDA 30 taken at line 37-37shown in FIG. 36. As shown, disc drive 20 is inserted into a memory cardslot 32 in PDA 30, preferably a slot that is designed to receive a TypeI CompactFlash® card. Substantially all of the first portion 266 of bodyassembly 24 is positioned inside slot 32, except for a small region 269which lies adjacent the gap between drive mechanism 20 and the face ofPDA 30. First portion 266 fits within, and is in all respectsstructurally and electrically compatible with, slot 32. For example,socket connector 26 in disc drive 20 mates with a correspondingCompactFlash pin connector 34 located at an internal end of slot 32.Integral rails 267 of lower housing 260 conform with the sides of slot32. As shown in FIG. 38, which is a view of PDA 30 without disc drive20, a rib 404 lines each side of slot 32. Ribs 404 mesh with grooves 406on rails 267 of lower housing 260, as shown in FIGS. 14 and 15.

[0080] Moreover, it is evident from FIG. 37 that a portion of cartridge10, a portion of cartridge tray 208, and a portion of disc 116 extendinto slot 32. This allows drive mechanism 22 to be made narrower andlimits the distance by which disc drive 20 protrudes from slot 32 (i.e.,the “overhang”).

[0081] Drive Mechanism

[0082] Drive mechanism or “pod” 22 includes the following components:

[0083] 1. An optomechanical carriage, which contains the laser,detectors, optics and fine servo motors for focus and fine tracking aswell as the electronic circuitry needed for servo and data detectionfunctions.

[0084] 2. An upper PCBA (smaller than PCBA 262 in body assembly 24) forterminating the interconnects and circuitry to support the spindle,servo and data detection.

[0085] 3. Flexible circuitry and designed service loops forcommunication with other electronics and to allow carriage movement,vertical pod movement, and installation of these components and thecarriage drive (coarse tracking) motor.

[0086] 4. A coarse servo mechanism, operated by a lead screw or linearmotor to move the optomechanical carriage to the desired point in thedataband.

[0087] 5. A spindle and spindle drive motor assembly.

[0088] 6. A latch mechanism for holding the drive mechanism inengagement to the media, or releasing it, and release buttons.

[0089] 7. A load button, which provides overtravel of the spindle toengage the media.

[0090] 8. A lift spring and cup to elevate the drive mechanism forcartridge insertion.

[0091] 9. A housing and cover.

[0092]FIG. 18 is a view of drive mechanism 22 from the bottom and FIG.19 is a view of drive mechanism 22 from the top with cover piece 310 andPCBA 308 removed. Referring to FIG. 18, drive mechanism 22 contains aspindle assembly 280, a data access opening 290 and an optomechanicalcarriage assembly 282. Spindle assembly 280 engages a central hole indisc 116. As described below, optomechanical carriage assembly 282contains a laser, a lens and other components for reading data from anoptical data storage disc through data access opening 290. As shown,spindle assembly 280 is located off center of drive mechanism to allowroom for electrical connections between body assembly 24 and drivemechanism 22 and to facilitate the reading of the data area of a disc.

[0093] Also shown in FIG. 18 are a spring-loaded cup 284, which biasesdrive mechanism 22 in a raised position, allowing the insertion of adisc through opening 246 (FIG. 5) when drive mechanism 22 is not latchedto body assembly 24. Spring-loaded cup 284 abuts against the externalsurface of top cover 206 of body assembly 24. Cartridge 10 is locatedprecisely to drive mechanism 22 by cartridge locating pins 288, alsoshown in FIG. 18, which fit into corresponding holes 304 in cartridge 10(see FIG. 9). Pins 288 are “bullet nose” pins. The radius cut onto theflanks of the insertion point is equal to the diameter of the pin. Thisshape offers a maximum acquisition zone for insertion into a hole 304and a minimum opportunity for binding or balking on insertion. Alsoshown in FIG. 18 are auxiliary datum pads 285 which locate cartridge 10in the proper orientation with respect to spindle assembly 280. Asindicated, two of the datum pads 285 are located at the bases oflocating pins 288. When a cartridge 10 has been inserted and drivemechanism 22 has been closed, locating pins 288 and datum pads 285project through openings 287 in lower housing 260 to make contact withthe surface of cartridge 10.

[0094] Referring now to FIG. 19, the top surface of optomechanicalcarriage assembly 282 is shown, along with a lead screw 296 (partiallyvisible in FIG. 18) that is used to provide coarse positioning for theread/write laser beam that emanates from optomechanical carriageassembly 282. Lead screw 296 is driven by a carriage drive (coarsetracking) motor 292 through a two-stage gear reduction unit 294.Anti-backlash gears may be used in the drive train. The bearing elementsfor lead screw 296 preferably contain at least one pre-loaded pair ofball bearings to keep friction low, but eliminate backlash in the motionof lead screw 296 along its axis of rotation.

[0095] A load button 302 is pressed by the user after a cartridge hasbeen inserted into disc drive 20, opposing the force of spring-biasedcup 284, causing drive mechanism 22 to become latched to body assembly24, and advancing an expandable collet into the central hole of opticaldisc 116. A flexible interconnect 305 connects PCBA 262 in body assembly24 to a PCBA 308 in drive mechanism 22, and a flexible interconnect 306connects the PCBA 308 in drive mechanism 22 to optomechanical carriageassembly 282. PCBA is removed from the view in FIG. 19 but is visible inthe cross-sectional view of FIG. 21.) In general, the components ofdrive mechanism 22 are mounted in a body member 299, which can be madeof a metal such as aluminum or magnesium or a plastic resin such as aliquid crystal polymer having a Young's modulus of at least 2.8×10⁴ MPa(4.4×10⁶ psi). A lift spring 300 which presses again cup 284 is enclosedin a cylindrical compartment 298 formed in body member 299.

[0096] Inside drive mechanism 22, flexible interconnect 305 has aserpentine service loop which is designed to allow flexible interconnect305 to retract smoothly into drive mechanism 22 as the assembly isclosed for operation. ZIF connectors on either or both of PCBAs 262 and308 may be used to facilitate assembly. FIGS. 20A and 20B show how theconfiguration of flexible interconnect 305 changes between the open andclosed positions of drive mechanism 22. From FIG. 17, it is clear thatdrive mechanism 22 is adjacent second the portion 268 of body assembly24 when drive mechanism 22 is in the closed position.

[0097] To service the motion of optomechanical carriage assembly 282along the tracking path, flexible interconnect 306 forms a single loopbetween the tail of carriage assembly 282 and PCBA 308. The carriage endof this flexible interconnect 306 circuit is connected to alaser/detector package for signal and data transfer, and to a fine servomotor to control focus and tracking. In an implementation using a linearmotor, it would also carry the coarse motor current. Again, a ZIFconnector on the PCBA 308 can be used to facilitate assembly.

[0098] A short flexible interconnect (not shown) may be used to connectcoarse tracking motor 292 to PCBA 308, although discrete wires or formedmotor terminals could also be used.

[0099]FIG. 21 is a cross-sectional view of drive mechanism 22 whichshows a PCBA 308 adjacent to a cover piece 310. Flexible interconnect306 is shown extending from PCBA 308 to optomechanical carriage assembly282. Also shown are spring cup 284 and lift spring 300, the upper end ofwhich abuts against the lower surface of PCBA 308. Spring cup 284 isshown extended from body member 299, in its position when drivemechanism 22 is not latched to body assembly 24. Load button 302 movesspindle assembly 280 vertically through the stator plate which isdirectly beneath load button 302.

[0100]FIG. 22 is an exploded view of drive mechanism 22, showing thecomponents described above. Also shown is a rail 312 along whichoptomechanical carriage assembly 282 slides and a slot 307 in bodymember 299 through which flexible interconnect 305 extends between PCBA308 in drive mechanism 22 and PCBA 262 in body assembly 24 Also,recesses 399 are formed in the side walls of body member 299. Guides 210slide in recesses 399 as drive mechanism 22 is opened and closed,preventing drive mechanism 22 from rocking when it is in the openposition.

[0101] Coarse Tracking Mechanism

[0102] The coarse tracking mechanism and spindle motor assembly 314 areshown in FIG. 23. Coarse tracking motor 292 is a brush-type, reversibleDC motor, such as a Canon model DN06-V*N*B, although a stepper motor orbrushless DC motor could also be used. Among the factors that determinethe choice of motor are bandwidth, power consumption, cost, reliabilityand durability.

[0103] Lead screw 296 and optomechanical carriage assembly 282 may becoated with or made from materials which mitigate the friction inherentin this type of actuator. Materials such as polytetrafluoroethylene(PTFE) or molybdenum disulfide can be used as a coating for threadedelements, and added to molding resins to optimize the tribology betweenlead screw and nut of such a driver. This can also reduce powerconsumption and improve servo response.

[0104] Coarse tracking motor 292 moves in response to a signal derivedfrom a position sensor on the fine tracking motor (described below). Thefine tracking motor follows the tracks on an optical disc, includingdisk runout, and accomplishes small seek movements. However, when thefine tracking motor is away from its center position by a specifiedaverage amount, lead screw 296 will be turned to advance or retract theoptomechanical carriage assembly 282 to a position near the center ofthe fine tracking motor travel. The two-stage spur gear reduction unit294 allows the use of a small, low current motor. Other gear reductionschemes could also be used, but spur gears are low cost and highefficiency. The gears in gear reduction unit 294 correspond roughly to120 diametral pitch gears, but they could also be special pitch ormetric module gears. The gear reduction unit may also containanti-backlash gears.

[0105] Spindle Motor Assembly

[0106]FIG. 24A is an exploded view of spindle motor assembly 314,including a spindle shaft 330, a disk platen 316, an expandable collet318 for disk retention, a spindle rotor magnet 326 and backing plate328, a spindle bearing/bushing 324, stator coils 320 and stator plate322, and load button 302. These parts are also shown (unnumbered) inFIG. 21.

[0107] Stator coils 320 and stator plate 322 are located just below loadbutton 302, and are both glued to upper PCBA 308. Load button 302 ispreloaded by the attraction of spindle rotor magnet 326 to stator plate322. Optionally, a spring element (not shown) may also be interposedbetween load button 302 and cover piece 310. Spindle bearing/bushing isa precision bushing which allows spindle shaft 330 to rotate and toslide in an axial direction. Load button 302 has a hardened face 302Awhich acts as a thrust bearing for a hardened, radiused end 330A of thespindle shaft 330. When pushed downward, load button 302 advances diskplaten 316 and collet 318 to seat a disk on platen 316 while resting inthe cartridge. With shutter 180 in the open position, expandable collet318 projects into the central hole 116A of disc 116 (see FIG. 4C). Thespindle rotating elements (i.e., rotor magnet 326, backing plate 328,shaft 300, platen 316 and collet 318) then retract to the run positionwhen the load button 302 is released.

[0108] Stator coils 320 are a standard brushless multi-phase drive forspindle rotor magnet 326, which is magnetized in “pie-slice” shapedsegments through its thickness in the axial direction. The north-southorientation of the magnetic material is in the same direction. Themagnetic material is preferably a barium ferrite ceramic, but it couldbe any of several others, including a rare-earth composite or hardmagnetic material, such as neodymium-iron-boron, samarium cobalt, etc.

[0109] Clamping the disk with an expandable collet and platen, asdescribed above, obviates the need to provide the disc with a magnetichub. This is desirable for reasons of cost, reliability, and size. Theclamping mechanism must be positive, which can be prohibitively complexfor media-in-cartridge. Using the force available through the manuallatching/loading of the system by the operator allows this to be donewithout consuming battery power, or providing complex load mechanisms.As described in the above-referenced application Ser. No. ______[Attorney Docket No. VMA004US], a raised ring can be provided on the“label” (downward facing) side of the cartridge to hold the disc awayfrom the cartridge bottom wall, but the position at which the disc restsis still more than 300 micrometers away from the run position of thedisc. That means that the spindle must be momentarily advanced to aclamping position, and then retracted to the run position. A plainspindle bearing/bushing 324 for spindle shaft 330, and load button 302,which acts as a magnetically loaded thrust bearing, allow this tohappen.

[0110]FIG. 24B shows a detailed view of platen 316 and collet 318.Collet 318 includes a plurality of flexible fingers 317 arrayedcircumferentially around a central hub 319. Platen 316 and collet 318are preferably made of plastic resin having a Young's modulus of 2.8×10⁴MPa (4.4×10⁶ psi) or higher with an admixture of PTFE. Selection of thematerial involves compromises between surface hardness, wear resistance,low friction, stiffness (high Young's modulus), and resistance to creep.One possibility would be a nylon 6 resin containing approximately 5%PTFE and 20% short glass fiber reinforcement.

[0111] As collet 318 is lowered into the central hole 116A of disc 116,the canted leading surfaces 317A of fingers 317 slide along the edges ofhole 116A until disc 116 is captured by the trailing surfaces 317B.During this process, disc 116 is pressed against the raised ring on theinterior of the bottom wall of the cartridge, the raised ring holdingdisc 116 sufficiently far above from the bottom wall of the cartridge toallow the bottom surface of disc 116 to clear the “peak” of each finger317. This distance is shown as Z3 in FIG. 24B. In the embodiment shown,canted leading and trailing surfaces 317A and 317B are angled at 45°with respect to vertical. Since disc 116 is typically very light, only asmall force is required to hold disc 116 firmly against platen 316.

[0112] This process is reversed when collet 318 is withdrawn from disc116. A similar raised ring on the upper surface of cartridge 10 preventsthe data are of disc 116 from coming into contact with the interiorsurface of the cartridge.

[0113]FIG. 39 shows a cross-sectional view of disc 116 inside cartridge10, showing raised rings that are used to prevent the disc from beingpressed flat against the top and bottom walls of the cartridge whencollet 318 is being inserted and withdrawn. Cartridge 10 has a sheetmetal top wall 104T and a sheet metal bottom wall 104B. The sheet metalis stamped to form a raised ring 400 in bottom wall 104B and a raisedring 402 in top wall 104T. The number 192 identifies a paper label thatis affixed to the outside of bottom wall 104B. To allow collet 318 toproject sufficiently into the central hole of disc 116 to trap disc 116on the trailing surfaces 317B, the height Z4 of raised ring 400 must beat least equal to the distance Z3 in FIG. 24B.

[0114] Carriage Assembly

[0115]FIG. 25 is a general view of optomechanical carriage assembly 282,which includes a carriage body 332, an optics assembly 334, and a finetracking/focus mechanism 336.

[0116] Carriage body 332 is a molded/cast part. Carriage body 332supports elements of optics assembly 232 and attachments for flexibleinterconnect 306 and provides the guided surfaces for the motion ofcarriage assembly 282 along the tracking path. It is coupled via leadscrew 296 to coarse tracking motor 292. Carriage body 332 also absorbsheat from the electronics, laser, and servo motors. It may be made ofmaterials which reduce friction so that the driving female threadedelement that meshes with lead screw 296 can be molded directly intocarriage body 332.

[0117] Optics assembly 234, which is described in greater detail below,includes a laser diode, servo detectors, beam distribution and splittingprisms, collimation and objective lenses, a wave retardation plate, areflective position flag, and a reflective power monitoring surface. Inaddition, some of the detectors may be mounted on substrates which alsoinclude signal amplification electronics.

[0118] Fine tracking/focus mechanism 336 includes shared magneticcircuits and five coils that together comprise a two-axis voice coilmotor used to position the readout objective lens (which is also part ofoptics assembly 334).

[0119]FIGS. 26 and 27 are exploded views of optomechanical carriageassembly 282 taken from different angles. Also shown in FIGS. 26 and 27are an anti-backlash mechanism that includes a threaded sleeve 333 and acompression spring 335. Carriage body 332 includes a first flange 332Awhich contains a threaded aperture that, as noted above, meshes withlead screw 296, and a second flange 332B that contains an unthreadedaperture. The central aperture of sleeve 333 likewise threaded to meshwith lead screw 296. Sleeve 333 is installed between flanges 332A and332B with a round end 333B projecting into the hole of flange 332B andwith compression spring 335 enclosing sleeve 333 and butting againstflange 332A and a shoulder 333A of sleeve 333. When lead screw 296 isthreaded into flange 332A and sleeve 333, compression spring 335 exertsa gentle outward pressure against flange 332A and sleeve 333. Thisprevents any slack or lost motion between optomechanical carriageassembly 282 and lead screw 296.

[0120] Optics Assembly

[0121]FIG. 28 illustrates a schematic view of optics assembly 334. Forpurposes of this description, the terms “up,” “down,” “above” and“below” are used in relation to FIG. 28.

[0122] The laser beam originates in a laser diode 338. Laser diode 338preferably provides a blue laser beam with a wavelength of 405 nm. Laserdiode may be a Cree model 405LD 500 or a Sanyo model LS5000. Use of a405 nm blue laser beam permits the track pitch on disc 10 to be reducedto 0.37 μm from the pitch of 0.74 μm required for a typical 600-700 nmred laser beam, for example.

[0123] Laser diode 338 is mounted on a heat sink 340 near the bottom ofa laser diode/detector substrate 343. A laser beam 342 emanates fromlaser diode 338 as a diverging, elliptical cone of light. Laser beam 342enters a rhombic prism 344 and is directed upward by internal reflectionin prism 344.

[0124] Rhombic prism 344 is attached to a half cube 346. A diagonalsurface between the rhombic prism 344 and half cube 346 is coated with apolarization sensitive layer, which forms a beam-splitting interface345. The predominant polarization of laser beam 342 causes it to passthrough beam-splitting interface 345 and continue upward. After laserbeam 342 leaves half cube 346, it enters a collimating lens 348.Collimating lens 348 converges laser beam 342 just enough to make thebeam a collimated (parallel ray) beam. Above collimating lens 348 is aquarter-wave retardation plate 350, which rotates the polarization oflaser beam 342 by 45 degrees about the axis of the beam.

[0125] On the upper surface of quarter-wave plate 350, shown in FIG. 29,is a small silvered area 350A, which reflects a portion of the upwardbound laser beam 342 back through quarter-wave plate 350. That reflected“beamlet” has its polarization rotated another 45 degrees as it passesagain through quarter-wave plate 350, so that its polarization is nowrotated 90 degrees from the polarization of laser beam 342 when it leftcollimating lens 348. When this “beamlet” encounters beam-splittinginterface 345, it is now reflected instead of transmitted. Thisreflected “beamlet”, shown at 352 in FIG. 28, is directed to a laserdiode 354 on substrate 343, where it is used to modulate the laser powercontrol loop.

[0126] The remainder of the outbound beam (minus the “beamlet”) proceedsupward towards an objective readout lens 356, which is supported by anobjective lens mount 358, shown in FIG. 30 from below. Protruding fromobjective lens mount 358 is small, shaped reflective element 360, whichreturns another portion of laser beam 342. Reflective element 360 may bemade of metal, and may be added to lens mount 358, or it may comprise areflective coating applied to a molded plastice feature. Its reflectivesurface may be planar or curved.

[0127] The portion of laser beam 342 that is reflected from reflectiveelement 360 is reflected in a direction that is determined by theposition of lens mount 358 along the “tracking axis.” The “trackingaxis” of lens mount 358, described further below, nominally coincideswith the axis along which laser beam 342 is reflected upward by therhombic prism 344. This second “beamlet” 362 returns in the same way asthe first “beamlet” 352, making a second pass through quarter-wave plate350, but on the opposite side of the main laser beam 342. Thepolarization of second “beamlet” 362 is likewise rotated another 90degrees and is therefore reflected by beam splitting interface 345towards substrate 343 where it illuminates a split position-sensitivephotodetector 364. Photodetector 364 is split horizontally, and thepower of “beamlet” 362 is distributed vertically between the two halvesof split photodetector 364 in proportion to tracking axis of objectivelens mount 358. The position of the spot formed by “beamlet” 362 onsplit photodetector 364 thus provides an indication of the position ofthe fine servo motor (described below) that controls the orientation ofthe tracking axis of lens mount 358.

[0128]FIG. 31 shows the respective positions of laser diode 354 andphotodetector 364 on substrate 343.

[0129] Referring again to FIG. 28, the rest of laser beam 342 proceedsupward through the readout objective lens 356 and is focused on thegrooves on optical disc 116 (not shown). Laser beam 342 is reflected bythe disc and passes back through objective lens 356, quarter-wave plate350 and collimating lens 348. Laser beam 342 is then reflected at beamsplitting interface 345 towards laser diode/detector substrate 343,where it is incident on a servo photodetector 366. As shown in FIG. 31,servo photodetector 366 has six segments (photodiodes). The segmentedstructure of servo photodetector 366 allows a determination of the beamdistribution and intensity as it returns from the disc and is reflectedat beam splitting interface 345.

[0130] The numerical aperture of lens 356 is high (e.g., approximately0.72) and therefore, when the collimated beam 342 is focused on areflective surface, a “cateye” reflector is formed. As a result, whenlaser beam 342 is focused exactly on the disc, the reflected beam willeffectively retrace its path and re-form as a collimated beam afterpassing back through objective lens 356. If the position of objectivelens 356 is above or below the position that creates an exact focus onthe disc, the return beam below objective lens 356 will converge ordiverge, i.e., when lens 356 is too close to the disc, the return beamwill be slightly convergent, and when lens 356 is too far from the disc,the return beam will be slightly divergent. The variation of theconvergence or divergence with focus error is proportional over a smallrange of focus error, and creates differences in the outputs of thesegments of servo photodetector 366. The focus error is determined bytaking the sums and differences of the segments of servo photodetector366 in horizontal and diagonal groups.

[0131] Because the surface of the disc is grooved, the return beam isalso diffracted. When the beam is centered on a track, the pattern ofthe return beam projected onto the servo photodetector 366 isessentially three superimposed spots: one bright central (or zero-order)spot, and two fainter, first-order diffracted spots, one above and onebelow the central spot and symmetrically overlapping the central spot.When the focused outbound beam moves slightly off-track, the projectedpattern of the reflected beam shifts, and the diffracted spots are nolonger symmetrically placed. This asymmetry produces differentialintensity changes along the vertical axis of servo photodetector 366.Tracking error signals are obtained by observing the difference betweenthe sum of the outputs of the upper segments and the sum of the outputsof the lower segments.

[0132] The intensity changes caused by the imprinted data pits aredetected by monitoring the sum of the outputs of all segments of servophotodetector 366.

[0133] Algorithms for controlling the tracking and focus of the laserbeam are well known and available from many sources. One tracking andfocus system is described in Kadlec et al., U.S. Patent ApplicationPublication No. US 2002/0110056, entitled “Digital Focus And TrackingServo System,” filed Sep. 10, 2001, and references cited therein, all ofthe foregoing being incorporated herein by reference in their entirety.

[0134] Fine Servo Motor

[0135] Fine tracking/focus mechanism 336 includes a fine servo motor370. In response to control signals, fine servo motor 370 adjusts theposition of objective readout 356 lens so as to maintain the laser beamin focus and follow the tracks on the disc. FIG. 32 is a view of finetracking/focus mechanism 336, and FIG. 33 is an exploded view of finetracking/focus mechanism 336 showing the components of fine servo motor370. Objective readout lens 356, shown at the center of finetracking/focus mechanism 336, is a component of both optics assembly 334and fine servo motor 370. As shown, objective lens mount 358 fits in aslot formed between walls 378 in a pole assembly 376.

[0136] The tracking motion of objective lens 356 is created by movingobjective lens mount 358 in the direction of the “tracking motion”arrows in FIG. 32. This motion is created with four “bent” trackingcoils 372, subdivided into two groups 372A and 372B. Fine servo motor370 contains two permanent magnets 374 which are affixed to poleassembly 376 with like poles facing the center of pole assembly 376. (InFIGS. 32 and 33 the north poles are shown facing inward.) This forms twomagnetic gaps, one on each side of the center of pole assembly 376, withmagnetic flux vectors directed symmetrically inward or outward. The fourtracking coils 372 are positioned such that one vertical arm 372X ofeach coil is located in the one of the magnetic gaps. (Conversely, theremaining vertical arms 372Y, shown in FIG. 33, are outside the magneticgaps between magnets 374.) Coils 372 are connected in series in such amanner that the currents in the vertical arms 372X of coils 372A flow inthe opposite direction to the currents in the vertical arms 372X ofcoils 372B, i.e., when current flows downward in the vertical arms 372Xof coils 372A, the current flows upward in the vertical arms 372X ofcoils 372B, and vice-versa. Depending on the direction of the currents,coils 372 and the remainder of fine servo motor 370 (including lens 356)will be subjected to an electromotive force in one of the directions ofthe “tracking motion” arrows.

[0137] Objective lens mount 358 is attached to four flexure wires 380,the other ends of which are attached to a mounting plate 382. Flexurewires 380 allow lens mount 358 and lens 356 to move in the direction ofthe “tracking motion” and “focus motion” arrows shown in FIG. 32 butprevent it from moving in an direction orthogonal to the tracking andfocus motions.

[0138] Two of flexure wires 380 also provide the electrical connectionsfor tracking coils 372. Both mounting plate 382 and objective lens mount358 are made of an insulating material such as a plastic resin having aYoung's modulus of 2.8×10⁴ MPa (4.4×10⁶ psi) or higher. Thus, flexurewires 380 are insulated from the rest of the assembly by the mountingplate 382 and objective lens mount 385.

[0139] Flexure wires 380 can be made of beryllium copper or some otherhigh yield-strength material to minimize damage in operation orassembly. Flexure wires 380 should have a low electrical resistance tominimize any damage from heating. They are preferably corrosionresistant and could be coated or sleeved for vibration damping, e.g.,with a thin elastomer film or molded part.

[0140] Using flexure wires 380 to carry current to tracking coils 372allows the movement of lens 356 to approximate a smooth, orthogonalmovement in tracking and focus directions. Using other wires to make theelectrical connections may introduce moments which disturb this motionin an uncontrollable way.

[0141] The vertical motion necessary to focus lens 356 is provided by arectangular coil 384, which is enclosed within the four tracking coils372 when fine servo motor 370 is assembled (FIG. 32). Coil 384 ispositioned in the magnetic gaps between permanent magnets 374, andprovides summed Lorentz forces which move coil 384 up or down whencurrent flows through it. For the reasons described above, coil 384 ispreferably supplied with current through the two flexure wires 380 thatare not used to supply current to tracking coils 372.

[0142] To minimize any tilting of lens 356 it is desirable that the netelectromotive force vectors provided by coils 372 and 384 in thetracking and focus directions, respectively, pass through the central ofgravity of fine servo motor 370 (including lens 356) and objective lensmount 358.

[0143] It will be understood that optics assembly 334 is only oneembodiment of an optics assembly that could be used in a disc drive ofthis invention. Optics assemblies having other structures may be used indisc drives fall within the broad scope of this invention.

[0144] As noted above, the user presses side release buttons 202together in order to unlatch drive mechanism 22 from the closed positionand thereby enable a cartridge to be inserted into the disc drive. Manydifferent forms of latch mechanism may be used to hold drive mechanism22 in the closed position. FIG. 34 shows one possibility. One of siderelease buttons 202 (not shown) is affixed to the end of one of pinmembers 386. A shank 388 projects from both sides of pin member 386 andfits into the lateral section of the T-shaped slot 212 in guide 210 whendrive mechanism 22 is in its closed, latched condition. Pin members 386are spring-biased, and when the user presses release buttons 202together, he acts against the force of the spring. As shown in FIGS. 18and 22, pin members 386 are mounted into recesses 387 in body member299, and the ends of pin members on which release buttons 202 areaffixed project through openings 389 in body member 299.

[0145] As pins 386 move axially inward (toward drive mechanism 22)shanks 388 clear the guides 210, allowing pins 386 to slide upward inthe vertical sections of T-shaped slots 212 and moving drive mechanism22 from its closed position (FIG. 20A) to its open position (FIG. 20B).After the user has inserted a cartridge, he depresses load button 302,forcing drive mechanism downward. Pins 386 slide downward in theT-shaped slots 212 until shanks 388 reach the lateral sections ofT-shaped slots 212 at which point shanks are again forced into thelateral sections of T-shaped slots 212, latching drive mechanism in theclosed position.

[0146] When the disc has been played, the user again presses buttons 202together and the above process is repeated. This time, however, a magnet(not shown) in drive mechanism 22 lifts leaf spring 222, freeing barb240 from the recess 193 in cartridge 10. With barb 240 disengaged fromrecess 193, spring arm 220 pushes the cartridge out of cartridge tray208 to the point where it can be removed by the user.

[0147] Coarse Tracking Mechanism Using Linear Motor

[0148]FIG. 35 shows an alternative embodiment in which a linear voicecoil motor is used instead of a rotary motor and lead screw to moveoptomechanical carriage assembly 282. The linear motor may provide ahigher bandwidth and may reduce the amount of travel needed in the finetracking motor. On the other hand, the linear motor may require morecurrent to operate than the lead screw system.

[0149] In the case of the linear motor method for coarse actuation, thefollowing innovations are proposed:

[0150]FIG. 35 shows the spindle motor assembly 314 and carriage assembly282 as it would be implemented using a voice coil motor. Carriageassembly 282 travels on a pair of rectilinear rods 390. Rods 390 serveas inner pole pieces for magnetic circuits that include U-shaped outerpole pieces 392 and permanent magnets 394. Magnets 394 are installedwith their field lines all pointing inward or outward with respect tothe vertical central plane positioned at the midpoint between magnets394 and rods/pole pieces 390 and 392. Thus the orientation of themagnetic fields is transverse to the tracking axis along which carriageassembly 282 moves. The magnetic flux runs in a circuit from the innerfaces of magnets 394 across the gap to the rods/pole pieces 390. Inrods/pole pieces 390 half of the total flux goes to the left (towardsspindle motor assembly 314) and half goes right, and then the flux (bothhalves) returns to the magnet through the U-shaped outer pole pieces392.

[0151] On opposite sides of carriage assembly 282 are coils 396. Coils396 are wired in series or parallel to cause the Lorentz forces to addwhen current flows through them. Preferably, PTFE, molybenum disulfideor another specialized anti-friction coating is placed on inner polepieces 390 and added to the plastic resin used to make the carriage body398. Thus, depending on the direction of the currents in coils 396,carriage assembly 282 moves in one direction or the other along thetracking axis. Focus control is provided by varying the current in asingle coil positioned between two permanent magnets, in the same manneras described above in connection with FIGS. 32 and 33.

[0152] Carriage assembly 282 is connected to a flexible interconnectwhich provides all of the servo inputs, coarse and fine, and the servoand data output.

[0153] While specific embodiments of this invention have been describedabove, it will be apparent to those of skill in the art that manyadditional and alternative embodiment are within the broad scope of thisinvention.

We claim:
 1. A disc drive for an optical data storage disc, said discdrive comprising: a body assembly having a connector located at one endof said body assembly and comprising a cartridge tray for holding acartridge which contains said optical data storage disc; and a drivemechanism comprising a spindle motor assembly and an optomechanicalcarriage assembly, said drive mechanism being movable from an openposition in which said cartridge may be inserted into said cartridgetray and a closed position in which said spindle motor assembly engagessaid disc; wherein said body assembly is sized for insertion into a datastorage card slot.
 2. The disc drive of claim 1 sized for insertion intoa slot designed to receive a CompactFlash storage card.
 3. The discdrive of claim 1 sized for insertion into a data storage card slot thatis designed to receive a memory card having a width in a directiontransverse to a direction of insertion of approximately 43 mm and athickness of approximately 3.3 mm.
 4. The disc drive of claim 1 whereinsaid drive mechanism is movable linearly between said open and closedpositions.
 5. The disc drive of claim 1 wherein said body assemblyincludes first and second portions, a substantial part of said firstportion being sized to fit in said memory card slot, said drivemechanism being adjacent to said second portion when said drivemechanism is in said closed position.
 6. The disc drive of claim 5wherein said cartridge tray extends into said first portion of said bodyassembly.
 7. The disc drive of claim 5 wherein a portion of saidcartridge extends into said first portion of said body assembly whensaid cartridge is inserted in said disc drive.
 8. The disc drive ofclaim 5 wherein a portion of said disc extends into said first portionof said body assembly when said cartridge is resident in said discdrive.
 9. A combination comprising a digital electronics device, a discdrive, and a cartridge, said cartridge comprising an optical datastorage disc, said digital electronics device comprising a memory cardslot, said disc drive being electrically connected to said digitalelectronics device by means of a first connector located at an end ofsaid disc drive and a second connector located at an internal end ofsaid memory card slot, a portion of said disc drive being positioned insaid memory card slot.
 10. The combination of claim 9 wherein said discdrive comprises a body assembly and a drive mechanism, said drivemechanism comprising a spindle motor, said first connector being locatedat an end of said body assembly.
 11. The combination of claim 10 whereina first portion of said body assembly is positioned in said memory cardslot and a second portion of said body assembly is positioned outsidesaid memory card slot.
 12. The combination of claim 11 wherein saiddrive mechanism is mounted adjacent said second portion of said bodyassembly and is located outside said memory card slot.
 13. Thecombination of claim 12 wherein said drive mechanism is mounted so as tobe movable between an open position and a closed position.
 14. Thecombination of claim 13 wherein said drive mechanism creates an openingto a cartridge tray in said disc drive when said drive mechanism is insaid open position.
 15. The combination of claim 13 wherein said driveis engaged to rotate said disc when said disc drive is in said closedposition.